Self-playing stringed instrument



March 18, 1930. RA-DTKE 1,751,248

SELF PLAYING STRINGED INSTRUMENT Filed March 8, 1928 3 Sheets-Sheet 1 & 1

March 18, 1930. B RADTKE 1,751,248

SELF PLAYING STRINGED INSTRUMENT Filed March 8, 1928 5 Sneets-Sheet 2 March 18, 1930. Y B, RADTKE 1,751,248

SELF PLAYING STRINGED INSTRUMENT Filed March 8, 1928 3 Sheets-Sheet 5 did 77 q s vices and-bows under electric control.

Patented Mar. 18, 1930 UNITED STATES rnrsnr err-res BRUNO RADTKE, OF LIBERTYVILLE, ILLINOIS,-ASSIGNOR'TO TMILLS NOVELTY COMPANY, vOF CHICAGO, ILLINOIS, A CORPORATION OF'ILLINOIS SELF-PL AYING STRINGED INSTRUMENT Application. filed March 8,.

This invention relates to self-playing musical instruments, andmore particularly to string instruments which are adapted'to be played by means of mechanical fingering de- In i instruments or" this character, the strings have avibratoryrmotion, particularly when the instrumentisequipped with devices for producinga tremolo effect by rapidly increasing and decreasing the tension on the strings,

thus causing longitudinal movement thereof. This is perhaps particularly true in the case otthevautomatic.cello, in connection with which my invention is illustrated in the ac- ..15. companying drawings.

With the fingering devices heretofore employed, this vibratory movement of the stringshas caused the same to slip with respect-.to the. lingering devices, thus interfering with the effectiveness of the latter by causing the grip thereofon the strings to be lessened.

The principalobject of the present invention is to provide, in a self-playing string in- 2 strument, a fingering device which is so constructed that the string-engaging element will retain its grip upon-0r contact with the string, notwithstanding vibratory movements of the latter.

.30 -O.ther objects and advantages of the invention will be apparent as it is'better understood. :trom the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment -3 thereo Referring to the drawings,

Figure 1 is a side elevational view of a selfplaying cello in which my invention is embodied;

Fig. 2 is a transverse sectional view, taken substantially on the section line 2-2 of Fig. 1;

Fig. 3 is a partial longitudinal section,

* taken substantially on the section line 83 in Fig. 2; and

"Fig. 4.is a plan view, showing a portion of the neck of thecello and the arrangement of the fingering devices with respect to the strings.

-Uponsaid drawings, illustrating the; pre- 1928. ,Serial No. 259,994.

"ferred embodiment of my invention, the reference character 21 indicates a cello, adjustably supported in a frame comprising a base :22, to whichv a'threaded rod 23 is pivotally secured at one end, as indicatd at 24, said rod carrying a bracket25, having a supportthe same manner as a self-playing violin of known type, such, for example, as that illustrated in United States Patent No. 807,871, dated December 19, 1905, and No. 855,021, dated May 28,1907.

The strings 35, 36, 37, and 38 arefixedly secured ,at the lower end of the cello and extendoverthe usual bridge 39 and the neck .41 of the cello, the opposite ends of said stringsbeing secured LO tuning levers 42, having arcuate portions 43, pivotally secured at a knife-edge pivot point 43 to the frame andv provided with lugs, or keepers, 44, said levers also being provided with hooks 45, which the strings are secured, the shanks of said hooks being threaded, as indicated at 46, and adjustably held in lugs 47 on the tension-ing lever 42 by means of nuts 48.

The desired spring tension is maintained upon the lever 42 by means of a spring 49, secured at one end to the lever 42 by means of-a connection 51, and at the other end to a tensioning device 52 by means of a connec- 1 tion53, said tensioning device being pivotally are attached at 61, a yielding connection being provided by means of springs 62.

The instrument is adapted to be played by means of rotating bows 63, carried upon shafts 64, driven by means of a power shaft 65, deriving its power from any suitable source, such as a motor (not shown), said shaft having hearings in a frame part 66 and a bracket 67, it'being understood that a separate bow is provided for each string, the bow shaft being adapted to be depressed by means of electro-magnets 68, in well known manner.

'1 he playing of the instrument is accom plished by a series of fingering devices operating in conjunction with the bows, said devices and the means for actuating the same being shown in detail in Fig. 2. Each finger icomprises a body part 69, pivotally supported at 'll-upon a side member 7 2 of a frame part 73, the fingers being normally held out of engagement with the strings by means of s rings 74, secured to a hooked part 75 on the finger and to a projection 76 on a side plate 7'? on the frame. Each finger is provided with an enlargement, or head part 7 8 at the forward end thereof, in which there is formed a V-shaped notch 7 9, adapted to engage the string in manner which will be evident from viewing Fig. 2. The finger is split centrally to provide upper and lower sect-ions 81 and 82, the latter carrying the string-engaging part 78.- The finger extends through slots in the plate 77 and in a plate 83, as indicated at 84 (see Fig. 3), and pieces of felt, or the like, indicated at 85, are provided upon the upper section of the finger, over the part thereof which is depressed in the slot 84 of the plate 2 83, thus holding said section'against movement in the longitudinal direction of the strings. Similar felt pieces 86 are provided upon the finger and disposed within the slot in the plate 77 and at the forward end of the finger, as indicated at 8?. The fingers are made of spring material and it will be evident that the lower section 82 is permitted to have a vibratory movement with the strings, to the extent permitted by the width of the slot 84 in the plate 83 without imparting this motion to the upper section 81 of the finger. This is a highly important advantage, since, if the string-engaging portion of the finger were held in fixed position, the vibratory motion of the strings, which in lengthwise direc-' tion, would produce a relative movement with respect to the finger, thus interfering with the play and the eficiency of operation of the machine.

For the purpose of moving the fingers into and out of engagement with the strings, a

series of solenoids 88 are provided, the same being mounted upon a pivoted head 89, shown clearly in Fig. 2, the same being pivotally secured at 91 to a frame part 92, the head being adapted to tion by means of a bolt 93 and nut 94 (see be secured in the down posi- 7 Fig. 2), the bolt extending through an arm 95 on the head 89 and a fixed frame part 96, the lowerend of said arm 95 being slotted, as indicated at 97, to facilitate movement of the head to and from operative position.

A series of binding posts 98 is provided upon a side plate 99 secured to the head, said binding posts having connections 101 with the solenoids, in the usual manner. The head 89 carries four bars 102, supported by rods 103 at opposite ends of said head, the under sides of said bars being provided with felt, or other cushioning material, 104 adapted to contact with the upper ends of the cores 105 of the solenoids, the lower ends 106 of which are adapted to engage the forward ends of the upper sections of the fingers at the point where the felt covering 87 is provided.

The arrangement of the fingers will be understood from an inspection of Fig. 4, from which it will be apparent that said fingers are arranged in pairs, each comprising one relatively short, straight finger, indicated at 107 in said Fig. 4, and one elongated finger 108, the forward end of which is offset, as indicated at 109, so that the string-engaging portion thereof is arranged in line with the corresponding portion of the finger 107. The fingers shown at the left of Fig. 4 are of special formation, having padded disks 111 in place of the regular, notched string-engaging portions, said disks being for the purpose of stopping the vibration of the strings when desired. The remaining fingers are constructed as shown in Fi 2 and arranged in pairs, as shown in Fig. 4 of the drawings.

)Vhen one of said solenoids 88 is energized, the core 105 thereof moves the associated finger downwardly, in obvious manner, into movement between the string and the. finger,

ed in accordance with the present invention,

whereas, with the fingering devices constructthe string-engaging portion of the finger may move with the string during vibration of the latter, notwithstanding the pressure exerted upon the finger by the core of the actuating solenoid. I

7 It is thought that theinvention and many of its attendant'advantages will be understood from the foregoing description, and it" will be apparent that various changes may be made in the form, construction, and arrangementof the parts without departing from the spirit and scope of the invention, or sacrificlng all of its material advantages, the

form hereinbefore described being merely a preferred embodiment thereof.

I claim:

1. In a self-playing stringed instrument, the combination of playing devices engageable with the strings, tremolo devices oper able to produce endwise movement of the strings, and fingers movable into and out of engagement with the strings, said fingers having string-engaging portions movable with the strings to avoid slippage between said fingers and strings as the latter are moved longitudinally by said tremolo devices.

2. In a self-playing stringed instrument, the combination of playing devices engageable with the strings, tremolo devices operable to produce endwise movement of the strings, fingers movable into and out of engagement with the strings, said fingers being split to provide string-engaging portions movable with the strings and portions adapted to be held against movement with said strings, and actuating devices engaging said last-mentioned portions of the fingers.

8. In a self-playing stringed instrument, the combination of playing devices engageable with the strings, tremolo devices operable to produce endwise movement of the strings, fingers movable into and out of engagement with the strings, and devices engageable with said fingers for moving the same into engagement with the strings, each said finger comprising a split member one part of which is adapted to be engaged by one of said actuating devices and to be held against movement with the string and the other part of which is adapted to engage the string and to move therewith during the playing of the instrument.

at. In a self-playing stringed instrument, the combination of playing devices engageable with the strings, tremolo devices operable to produce endwise movement of the strings, fingers movable into and out of engagement with the strings, devices engageable with said-fingers for moving the same into engagement with the strings, each said finger comprising a split member one part of which is adapted to be engaged by one of said actuating devices and to be held against movement with the string and the other part of which is adapted to engage the string and to move therewith during the playing of the instrument, and means for holding said first-mentioned part of the finger against movement with the string.

5. In a self-playing stringed instrument, the combination of playing devices engageable with the strings, tremolo devices operable to produce endwise movement of the strings, fingers movable into and out of engagement with the strings, devices engageable with said fingers for moving the same into engagement with the strings, each said finger comprising a split member one part of which is adapted to be engaged by one of said actuating devices and to be held against movement with the string and the other part of which is adapted to engage the string and to move therewith during the playing of the instrument, and means for holding said firstmentioned part of the finger against movement with the string, said means comprising a slotted bracket in which the finger is movable toward and away from the strings and means upon the first-mentioned part of said finger whereby the same is held against transverse movement in said slot, the secondinentioned part of the finger having suflicient clearance in said slot to permit movement thereof with the string.

In witness whereof, I hereunto subscribe my name to this specification.

BRUNO RADTKE. 

